1. Field of the Invention
This invention relates to an apparatus for providing a coincident rotating laser beam and gas jet.
2. Description of the Prior Art
Among the many important applications of lasers are materials processing and machining, including welding, drilling, perforating, cutting, scoring, and marking. There are commercially available laser systems to perform all these operations on a variety of materials, such as plastics, ceramics, metals, etc. These systems typically comprise the following elements: a laser having the emission wavelength, power, and other parameters appropriate to the particular application and material; a beam delivery system to direct the laser beam to the workpiece; a workpiece handling system to hold and, optionally, move the workpiece; controls for the system's elements; and auxiliary equipment, which may be required for certain applications.
It is often desirable to move a laser beam in a circular pattern relative to a workpiece; for example, to cut round holes (trepan) or make perforations or welds in a circular pattern. To accomplish that, the beam delivery system may include a focusing lens that rotates in the plane of the lens on an axis that coincides with the laser beam. Alternatively, the beam may be rotated by a rotating mirror. Still another alternative is to move the workpiece, while either maintaining a stationary laser beam or coordinating the movement of the beam and workpiece. Moving the workpiece is inexpedient when the workpiece is massive and/or must be moved rapidly.
In certain materials-processing and machining applications, it is desirable to direct a gas stream to the spot on the workpiece where the laser beam impinges. Depending on the process, the gas may be an inert-, oxidizing-, or reactive-gas. Some applications require both that the laser beam move in a circular pattern and that a gas impinge on the same spot as the laser beam. The prior art apparatuses and methods that have been designed for those applications have several drawbacks. The apparatuses tend to be complex, expensive, and unreliable. Furthermore, they require alignment of the laser beam and gas nozzle--a tedious and time-consuming operation--each time either a lens or nozzle is replaced.